Singlet oxygen (1O2) is a cytotoxic reactive oxygen species that can play a key role in photodynamic therapy and a variety of important processes in plants. Singlet oxygen can also be used as a secondary analyte in biological assays (e.g., the Alpha technology from PerkinElmer). Thus, researches have focused on detection and quantification of singlet oxygen in vitro and in vivo.
Fluorescent probes showing response to singlet oxygen have been used in the detection or quantification of singlet oxygen. However, currently available fluorescent probes suffer from major drawbacks, such as being not suitable for in vivo applications (e.g., intracellular imaging).